|Rank|Name|Nationality|Time|
|---|---|---|---|
||Mark Henderson|United States|54.11|
||Eduardo Piccinini|Brazil|54.63|
||Brian Alderman|United States|54.75|
|4|Francisco Sánchez|Venezuela|54.99|
|5|Edward Parenti|Canada|55.23|
|6|Diego Cuenca|Colombia|55.67|
|7|José Meolans|Argentina|55.91|
|8|Ruben Calderon|El Salvador|56.04|

Question: how many swimmers swam the 100 meters in under 55 seconds?
Answer: 4